View with An overview of Cement Industry 1.1 HOW IS CEMENT MADE? Cement is a hydraulic binder. That means it is a material which sets and hardens when mixed with water. The raw materials which go into the production of cement, primarily limestone and shale, are extracted from a quarry by blasting, or mining. They are then finely crushed and ground and transported to the plant, where they are stored and homogenized. The grinding process provides a fine powder known as raw meal, which is then preheated and then enters the kiln (A. Chattopadhyay, 2004). Flames reaching temperatures of 2000° C heat the material to about 1500° C, before drastically cooling it by air blasts. This burning process produces cement clinker, the basic material required for the production of cement. The clinker and gypsum (hydrated calcium sulphate) are finely ground together to obtain pure cement, which is also known as Ordinary Portland Cement (OPC). Secondary constituents are then added to make blended cement like Portland Pulverized fuel ash Cement (PPC) etc. Finally, the finished products are stored in large silos from where they are dispatched in bulk or in bags to where they will be used. (“Cement Manufacturing Process”. 2003)
The production of clinker does not take place in Bangladesh. This is because the country lacks the raw materials namely limestone and shale, for the production of clinker. Therefore, it is imported from countries like India and China. The cement manufacturing stage that takes place in Bangladesh is the grinding of clinker and gypsum together to obtain pure cement.